A paste filling method and paste filling equipment are disclosed in Japanese Patent Application Publication No. 2001-203437. The paste filling equipment fills a paste as a fluidized material in a hole having a bottom as a blind via-hole (i.e., a half penetrate hole).
FIG. 4A shows the above paste filling equipment 100. In the paste filling equipment 100 shown in FIG. 4A, a substrate 101 having the blind via-hole 102 is disposed on the top of a base 201. The substrate 101 is vacuumed up through a suction opening 201a and a vacuum exhaust path 201b so that the substrate 101 is stuck and fixed on the base 201. A frame 202 is disposed on and contacts an outer periphery of the substrate 101 except for a paste-to-be-filled region of the substrate 101. On the top surface side of the substrate 101, a vacuum nozzle 205 is disposed on and contacts the substrate 101. Further, a paste 207 is accumulated in a space surrounded by the sidewall of the vacuum nozzle 205, the surface of the substrate 101, and the sidewall of a squeegee for squeezing the paste. After that, while air is vacuumed by the vacuum nozzle 205, the vacuum nozzle 205 and the squeegee 204 are simultaneously and relatively displaced in parallel to the surface of the substrate 101, so that the paste 207 is filled in the blind via-hole 102, which is depressurized.
FIGS. 4B and 4C are enlarged cross sectional views explaining the method for filling the paste 207 into the blind via-hole 102 by the paste filling equipment 100. The paste filling equipment 100 shown in FIG. 4A fills the paste 207 into the blind via-hole 102 while the blind via-hole 102 is evacuated by the vacuum nozzle 205. Therefore, the paste filling equipment 100 does not have a problem about remaining the air in the bottom of the blind via-hole 102, compared with a case where the paste 207 is filled in the blind via-hole 102 having atmospheric pressure. Here, in the blind via-hole 102 having atmospheric pressure, the air is remained because the air disposed in the bottom of the blind via-hole 102 is not exchanged to the paste 207.
On the other hand, the space surrounded by the sidewall of the vacuum nozzle 205, the surface of the substrate 101 and the sidewall of the squeegee 204 is in a state of atmospheric pressure, and the paste 207 is accumulated in the space. Therefore, the paste 207, which is under the atmospheric pressure, as shown in FIG. 4B, is delivered with involving the air disposed in the space in accordance with a movement of the squeegee 204. Accordingly, in the paste filling equipment 100 shown in FIG. 4A, a bubble 207v is produced in the paste 207. The paste 207 involving the bubble 207v is filled in the blind via-hole 102, as shown in FIG. 4C. After the bubble 207v is involved in the blind via-hole 102, the bubble 207v cannot be removed in a later process. Therefore, in the blind via-hole 102 having the paste 207 with the bubble 207v, the paste 207 is not filled sufficiently, so that it may cause a conductive fault.